The human body's ability to maintain a constant environment is essential to its survival. This capability is referred to as homeostasis. Homeostatic mechanisms keep the body near a set point, based on the sensitivity of central nervous system nuclei, which is an ideal value for that particular person. An example of a homeostatic mechanism is a negative feedback mechanism. Any deviation from the set point is made smaller.
             This mechanism does not prevent variation, it only helps keep the variation near the set point. Many negative-feedback mechanisms have three components; a receptor, a control center and an effector. A receptor monitors the significance of the variable. The control center is where the set point is established. The effector has the ability to change the variable.
             The set point varies from person to person. The body usually does not maintain its set point exactly but instead it fluctuates and declines around this point bringing forth a normal range of values. When the body undergoes a physical stressor; such as exercise, a secondary set point is established.
             The Schneider test measures the recovery rate, the rate at which the body moves back to the original set point once a stressor is removed. It determines the recovery limit of the cardiovascular system. It is based on the measurement of heart rate and blood pressure before, during and after exercise, a stressor in this case is standing and moderate exercise. This system was developed by Dr. Schneider after World War I in order to evaluate combat preparedness and overall fitness of American aviators.
             Exercise: 15 sec.- 88 Score: 16
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